Cassiopeia was launched 15 November 1942 as liberty ship SS Melville W. Fuller by Permanente Metals Corporation, Richmond, California, under a Maritime Commission (MARCOM) contract, MCE hull 504; sponsored by Mrs. C. F. Calhoun; acquired by the Navy 27 November 1942; and commissioned 8 December 1942.

From this base, she offered essential support to the operations in the consolidation of the northern Solomons, carrying the varied necessities of war throughout the South Pacific.

Another resupply mission and a brief repair period in New Zealand preceded her resumption of South Pacific operations in November.

[4] This pattern of ferrying vital supplies in the South Pacific alternating with voyages to New Zealand to reload continued until 6 June 1945, when Cassiopeia cleared Auckland for San Francisco, the Panama Canal Zone, and Norfolk, where she arrived 25 October.

[4] Cassiopeia was laid up in the National Defense Reserve Fleet, James River Group, Virginia, on 21 November 1945.